More than 120 million American adults live with chronic illnesses, and millions of those people are parents. But when we picture someone with a chronic illness we don't usually picture a mom, but some high-profile Hollywood actors are changing that.

In a recent essay for Shondaland, mom of two Jamie Lynn Sigler explained how multiple sclerosis impacts her family, but that living with a chronic illness doesn't make her any less of a mother to her sons.

"MS — any chronic illness, really — becomes your whole family's disease, not just your own. It affects our daily choices, and while sometimes I resent that, it has also made me see how strong I am. I have two little boys now. Beau is 5-and-a-half, and Jack is 14 months. I am there for them each and every day. I walk Jack every day in his stroller, around the block, no matter how long it takes me. I take Beau to hockey and karate and baseball, and sit on my chair and cheer him on. I am definitely participating in life the way I always dreamed, but it's not without challenges," she writes.

Sigler was diagnosed with MS before becoming a mom and notes that while her disease has been stable for more than a decade, pregnancy still terrified her.

"A million thoughts ran through my head. What if he runs off and I can't chase him one day? What if I can't carry him up and down the stairs? What if he won't want to play with me because I can't be the 'fun mom' who runs on the beach with him, or chases him around the house?"

Sigler says she does have days where she doesn't move fast and needs help up the stairs, "but in the face of the daily fears that I have of not being enough, my two little boys give me all the love and reassurance I'll ever need. They only know this one mommy."

For Sigler, her life-changing MS diagnosis came before motherhood, but for her friend and fellow actor Selma Blair, it came afterward. For years Blair struggled with unexplained exhaustion and pain and felt ignored by doctors who attributed her experience to being worn out by single motherhood.

"Ever since my son was born, I was in an MS flare-up and didn't know, and I was giving it everything to seem normal," she told Good Morning America. "And I was self-medicating when he wasn't with me. I was drinking. I was in pain. I wasn't always drinking, but there were times when I couldn't take it."

Thankfully, Blair is now getting the help she needs for her illness, and like Sigler, she's being open about her journey in the hopes of helping other parents who are dealing with MS and other chronic illnesses.

"I'd drop my son off at school a mile away, and before I got home, I'd have to pull over and take a nap. And I was ashamed, and I was doing the best I could, and I was a great mother. But it was killing me."

Thankfully, Blair is finally getting the help she needs. She famously walked this year's Oscar red carpet with a cane, but as she wrote in a recent Instagram caption, waking with an aid doesn't change her relationship with her son: "I am still the mom."

Chronic illness doesn't define these mothers, and it shouldn't define all the other moms who are dealing with health issues but still raising their families.

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